Electric circuit interrupter



Jan. 8, 1946. H. E. cox 2,392,647

ELECTRIC CIRCUIT INTERRUPTER Filed Aug. 18, 1945 GQR lo 26 A Inventor:Harol d E. Cox,

His Attorney- Patented Jan. 8, 1946 ELECTRIC CIRCUIT INTERRUPTER HaroldErnest Cox, London, England, asslgnor to General Electric Company,'acorporation of "New York Application August 18,1943, Serial No. 499,041

In Great Britain November 3, 1942 7 I 5 Claims.

My invention relates to electric circuit interrupters and moreparticularly to fluid blast circuit interrupters in which the arc gap istraversed by a high velocity blast of fluid, such as air, to causeextinguisliment of the arc drawn.

In fluid blast circuit interrupters and particularly air or gas blastcircuit breakers for high voltage applications, it has been the usualpractice to provide a source of gas underlpressure such as a gascontainer or storage reservoir, which comprises a part of the circuitbreaker and often is formed as an integral part of the frame work uponwhich the circuit breaker is built. A blast of gas under pressure forarc extinguishing purposes is released from such source which gas hasheretofore been required to traverse an insulating tube of sufficientlength to withstand the voltage to ground between the relatively movablecontacts of the circuit breaker and the source of fluid under pressure.For Very high voltages this insulating tube is of considerable lengthand in these cases the construction entails ineff ciency in that time istaken for the gas or fluid to pass from the source to the contacts whereth fluid blast is desired. In addition, with a considerable distance tobe traversed there is a loss of pressure due to pipe friction and thelike. Moreover, the insulating tube carrying the fluid from the sourceto the contacts is expensive to construct satisfactorily and being ofconsiderable volume entails using up a corresponding amount of fluidunder pressure in filling this tube before fluid is available toextinguish the are drawn. In addition, during an interrupting operationthe pressure drop in the fluid flowing from the source to the contactsmay cause condensation of moisture in the insulating tube with theresultant danger of arcing between the parts of the circuit interrupterat high potential and the parts at ground potential because of thismoisture in the insulating tube.

It is an object of my invention to provide a new and improved gas blastcircuit breaker in which all danger of arcing due to condensation ofmoisture in the parts connecting high and low potential portions of theapparatus is substantially eliminated.

It is another object of my invention to provide a fluid blast circuitbreaker having improved efficiency of performance due to increased speedof operation and better utilization of the available l gas pressurecombined with simplification in the number and construction of itsconstituent components. I

Further objects and advantages of my inven tion will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

For a better understanding of .my invention reference may be had to theaccompanying drawing, in which thesingle figure thereof is a schematicdiagram, partly in section, of a fluid blast circuit interrupterembodying my invention. v p

' Referring now to the drawing, I have illustrated a fluid or gas blastcircuit interrupter generally indicated at I0 comprising an insulatingare extinguishing chamber II within whichare mounted a pair of relativelmovable contacts I2 and I3. Contact I2 has been illustrated asa-stationary or fixed contact which is electrically connected to a lineterminal I4. Contact I3, on the other hand, has been illustrated as amovable rod contact operatively connected to a piston I5 reciprocatinglymounted within a cylinder I6, which in turn is supported within arcingor are extinguishing chamber II. A suitable spring I l biases contactsI2 and I3 to a closed position. Movable contact I3 is electricallyconnected through cylinder I6 andassociated conducting apparatus withtheline terminal I8. Insulating arcing chamber II is also provided with aportion of reduced cross section or a nozzle'l9 which connects theinterior of arcing chamber II to atmosphere through an opening 20. ,l

' Mounted closely adjacent to arcing chamber I I so as preferably to beat substantially the same potential as contact I3 for example, I haveprovided a reservoir 2| which contains fluid, such as air or gas, underpressure. Reservoir 2I is connected to arcing chamber I I through avalve generally indicated at 22 to be described in greater detailhereinafter. Upon opening of valve 22 fluid under pressure fromreservoir 2I enters arcing chamber II through conduits 23 and 24, thelatter of which is provided with openings, such as 25. This fluid willproduce an arc extinguishing blast through nozzle I9 adjacent relativelymovable contacts I2 and I3. Cylinder I6 is provided with openings, suchas 26', so that fluid under pressure entering these openings from areextinguishing chamber I I may cause relative separation of con- .tactsI2 and I3 in a manner well understood by those skilled in the art. Uponopening of main blast valve 22, as will be described in reater detailhereinafter, fluid under pressure from reservoir 2I will enter arcingchamber as well as cylinder Iliand due to'thepressure drop whichresults. condensation of moisture may occur in the fluid passagewayssuch as in conduits 23 and 24. However, since reservoir 2|, conduits 23and 24, and the relatively movable contacts are substantially at thesame potential there is-no danger of undesirable arcing by virtue ofsuch condensation of moisture.

Since the fluid blast circuit breaker described thus far is particularlyadapted for high voltage application, I have illustrated the arcingchamber, interrupting contacts, reservoir 2|, and blast valve 22, assupported upon a suitable insulator 21 which in turn may be mounted on agrounded frame work 28.

My invention is particularly concerned with an arrangement for operatingblast valve 22 from a point of low potential, such as ground potential,without the necessity of any mechanical connection to blast valve 22.Furthermore, my invention is concerned with an arrangement forreplenishing the fluid under pressure in reservoir 2| without any dangerof moisture condensation which would cause arcing between the highpotential portions and the low potential portions of the system.

To eliminate the necessity of a mechanical connection, main blast valve22 has been illustrated as of the balanced pressure type. Although thisbalanced pressure type of valve may comprise any of the well known formsof valves, such for example as are disclosed in United States LettersPatents 1,912,024, 2,310,130 or 2,315,991, I have chosen to illustrateblast valve 22 as of the type disclosed in Patent 1,912,024 in whichoperation of the valve is obtained by releasing the pressure on one sideof the piston. It should be understood, however, that operation of blastvalve 22 might equally well be obtained by some other variation ofpressure such as disclosed in Patent 2,315,991 referred to above.

As illustrated in the drawing, main blast valve 22 comprises a valvemember 30 adapted for sealing engagement with the end of conduit 24.This valve member 30 is furthermore mounted on a piston 3| which isreciprocable in a cylinder 32. A suitable spring 33 biases valve member30 mounted on piston 3| to the closed 'position. Under steady stateconditions, the forces acting on piston 3| by virtue of the fluid underpressure, substantially neutralize each other and the force of spring 33is the only force urging valve member 30 to the closed position. Thelower end of cylinder 32 is connected through an insulating tube 34 ofconsiderable length, to a source 35 of fluid under pressure which ispreferably main tained at ground potential, or in any event, at asubstantially lower potential than the potential of valve 22. Piston 3|of main blast valve 22 is provided with a small passage 36interconnecting the cylinder 32 below piston 3| with the space abovepiston 3| so as to balance the pressures operating on the upper andlower surfaces of the piston under steady state conditions. If thepressure on the lower side of piston 3| were suddenly released thepressures acting on piston 3| would be unbalanced and opening of valvemember 30 would occur. To accomplish this I provide a control valve 31also of the balanced pressure type and illustrated in the drawing assubstantially identical with main blast valve 22. Control valve 31comprises a piston 38 reciprocatingly mounted in cylinder 39. A valvemember 40 mounted on the upper end of piston 38 controls the connection.of insulating tube 34 with atmosphere through a conduit 4|. A smallpassageway 42 in piston 38 permits the pressures on piston 33 above andbelow the piston to be balanced under steady state conditions, in whichcase a spring 43 is provided to force valve member 4|! into sealingengagement with conduit 4|. Control valve 31 is operated in the samemanner as blast valve 22 and such operation is accomplished by releasingthe pressure below piston 33 through operation of a pilot valve 44 whichis biased to the closed position by means of a spring 45. Pilot valve 44may be operated by any suitable means, such for example as theelectromagnetic means 45 illustrated in the drawing. Control valve 31and pilot valve 44 are preferably mounted in any suitable manner (notshown) with the grounded frame work 28 of the circuit breaker III. Inorder to prevent the escape of any substantial amount of fluid underpressure from source 35 to atmosphere through conduit 4| when controlvalve 31 is open, I provide an orifice 41 between source 35 andinsulating tube 34 which is made as small as is convenientlypracticable.

It will be evident that although I have illustrated control valve 31which is in efiect a pilot valve for blast valve 22, as controlling theoperation of only a single pole of a circuit breaker, it will be obviousthat it could equally well be used to control the operation of theplurality of poles of a polyphase circuit breaker. Also if the circuitbreaker employed a plurality of sets of relatively movable contactsconnected in series with one another, control valve 31 might be used tocontrol a blast of fluid for both sets of contacts.

Under steady state conditions as indicated in Fig. 1, fluid underpressure from source 35 will flow through the restricted openings 41 and35 so that reservoir 2| is maintained at the same pressure as source 35.Due to the balancing of pressures on either side of pistons 3| and 33,springs 33 and 43, respectively, maintain valve members 30 and 40 in theclosed position. Upon opening of pilot valve 44, the pressure belowpiston 38 of control valve 31 is released so that valve member 40 movesaway from conduit 4| with the result that the pressure below piston 3|of main blast valve 22 is also rapidly released to cause valve member 30to move away from conduit 34, whereupon fluid under pressure fromreservoir 2| is supplied to arcing chamber |l. Any condensation ofmoisture between reservoir 2| and arcing chamber II will cause noundesirable arcing, since the parts are at substantially the samepotential. Furthermore, no condensation within insulating tube 34 willoccur with the consequent danger of arcing between the high potentialportions of the apparatus and the grounded portions of the apparatus. Assoon as pilot valve 44 is closed the pressures on piston 3| of blastvalve 22 and on piston 33 of control valve 3] proceed to balance andneutralize each other so that the springs 33 and 43 force valve members30 and 40 to their closed positions. The pressure in reservoir 2| isbuilt up by the flow of fluid through orifice 41 and small passageway35.

It will be observed that the insulating means 34 defining the fluidpassageway extending between source 35 and reservoir 2| serves a dualpurpose, i. e., it provides the means for replenishing the fluid inreservoir 2| from source 35 and furthermore is the agency by which mainblast valve 22 is controlled through variation of pressure in insulatingtube 34.

It will be apparent to those skilled in the art that my invention is notlimited to the particular construction shown, but that changes andmodifications may be made without departing from the spirit and scope ofmy invention, and I aim in the appended claims to cover all such changesand modifications.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a fluid blast circuit breaker, an insulating supporting member. apair of relatively movable contacts supported by said member, areservoir for fluid under pressure, valve means for causing a blast offluid from said reservoir to be produced adjacent said contacts for areextinguishing purposes during a circuit interrupting operation, saidreservoir and valve means being at substantially the same potential asat least one of said contacts, a source of fluid under pressuremaintained at a potential substantially lower than the potential of saidreservoir and valve means, insulating means defining a fluid passagewayconnected between said reservoir and said source for supplying saidreservoir with fluid under pressure, and means for controlling saidvalve means solely by controlling the fluid condilions in saidpassageway.

2. In a fluid blast circuit breaker, an insulating supportin column. apair of relatively movable contacts supported by said column, areservoir for fluid under pressure supported by said column. valve means[or causing a blast of fluid from said reservoir to be produced adjacentsaid r contacts for are extinguishing purposes during a circuitinterrupting operation, said reservoir and valve means being atsubstantially the same potential as at least one of said contacts, asource of fluid under pressure maintained at a potential I substantiallylower than the potential of said reservoir and valve means insulatingmeans defining a fluid passageway connected between said reservoir andsaid source for supplying said rescrvoir with fluid under pressure, andmeans for controlling said valve means solely by controlling the fluidconditions in said passageway.

3. In ahigh voltage fluid blast circuit breaker. an insulatingsupporting column, a pair of relatively movable contacts mounted on saidcolumn, a reservoir [or fluid under pressure mounted on said column.valve means for causing a blast of fluid from said reservoir to beproduced adjacent said contacts for are extinguishing purposes during acircuit interrupting operation, said reservoir and valve means being atsubstantially the same potential as at least one of said contacts. asource of fluid under pressure maintained at a potential substantiallylower than the potential of said reservoir and valve means, insulatingill means defining a fluid passageway connected between said reservoirand said source for supplying said reservoir with fluid under pressure,and means for controlling said valve means solely by controlling thefluid conditions in said passageway.

4. A fluid blast electric circuit interrupter for controlling anassociated electric circuit comprising an insulating supporting member,an are extinguishing chamber-supported by said member, a pair ofrelatively movable contacts mounted in said chamber, a reservoir forfluid under pressure supported adjacent to said chamber so as to b atsubstantially the same potential as at least one of said contacts, meansincluding a balanced pressure type of blast valve interconnecting saidreservoir with said chamber to produce a blast of are extinguishingfluid from said reservoir adjacent said contacts during a circuitinterrupting operation, insulating means suflicient to withstand thepotential of said associated circuit deflning a fluid passageway connected to said blast valve, a control valve for causing a variation inthe pressur of the fluid in said passageway to initiate operation ofsaid blast valve, a source of fluid under pressure, and means includingsaid fluid passageway for interconnecting said reservoir and saidsource.

5. A fluid blast electric circuit interrupter for controlling anassociated electric circuit comprising an insulatin supporting member,an are extinguishing chamber supported by said member. a pair ofrelatively movable contacts mounted in said chamber, a reservoir forfluid under pressure supported adjacent to said chamber so as to be atsubstantially the same potential as at least one or said contacts, meansincluding a balanced pressure type of blast valve interconnecting saidreservoir with said chamber to produce a blast of arc extinguishingfluid from said reservoir adjacent said contacts during a circuitinterrupting operation, a source of fluid under pressure from which thefluid in said reservoir is adapted to be replenished following a circuitinterrupting operation, means including insulating means defining afluid passageway interconnecting said source and said reservoir, and acontrol valve connected to the end of said passageway adjacent saidsource to cause upon operation thereof a variation in the fluid pressurein said passageway to unbalance the balanced pressures of said blastvalve and cause opening thereof.

HAROLD ERNEST COX.

